A control system of automobiles, aircrafts, ships or electronic devices for home use or business use is further complicated with increased accuracy, and correspondingly the integration density of small electronic components on a circuit board is continued to increase. As a result, it is strongly requested to solve malfunction or shortening of lifetime of the electronic components due to heat generation of the periphery of the circuit board.
To implement rapid heat dissipation from the circuit board, conventionally, measures such as configuring the circuit board itself of a material excellent in heat dissipation, mounting a heat sink, and driving a heat dissipation fan are singly taken, or a plurality of these measures are combined to be taken. Among these, the measures of configuring the circuit board itself of the material excellent in heat dissipation, for example, diamond, aluminum nitride (AlN), cubic boron nitride (cBN), or the like, extremely increases the cost of the circuit board. Additionally, placement of the heat dissipation fan causes problems of malfunction of a rotating machine such as a fan, necessity of maintenance for preventing malfunction, and difficulty in securing of installation space. On the other hand, a heat dissipation fin is a simple member capable of increasing a surface area by forming many columnar or flat plate-like projection portions using high thermal conductive metal (for example, aluminum) to enhance heat dissipation, and therefore is generally used as a heat dissipation component (refer to Patent Document 1).
Recently, for the purpose of reduction in a load to global environment, movement to gradually convert a conventional gasoline-powered vehicle or a diesel vehicle into an electric automobile is becoming more active in the world. Particularly, China, as well as European countries including France, Netherlands, and Germany, declares to completely switch from gasoline-powered vehicles and diesel vehicles to electric automobiles by the year of 2040. For the spread of the electric automobiles, there are problems such as installation of many charging stands in addition to development of high performance batteries. Particularly, technological development for enhancing a charging/discharging function of a lithium automobile battery becoming a big problem. The fact that the automobile batteries cannot sufficiently exert a function of charging/discharging under a high temperature of at least 60 degrees Celsius is well known. Therefore, similarly to the circuit board previously described, it is important to enhance heat dissipation of the battery as well.
In order to implement rapid heat dissipation of the battery, a structure, in which a water-cooling pipe is disposed in a housing made of metal excellent in thermal conductivity such as aluminum, many battery cells are disposed in the housing, an adhesive rubber sheet is disposed between the battery cells and a bottom surface of the housing, is employed. Hereinafter, description is made with reference to the drawing.
FIG. 9 is a schematic sectional view of a conventional battery. A battery 100 of FIG. 9 includes many battery cells 101 on an inner bottom surface 103 of a housing 102 composed of aluminum or aluminum base alloy. In a bottom section 104 of the housing 102, water-cooling pipes 105 for allowing cooling water to flow are provided. The battery cells 101 are fixed to the inside of the housing 102 with a rubber sheet (for example, a sheet made of room temperature-curable silicone rubber) 106 interposed between the bottom section 104 and the battery cells. In the battery 100 having such a structure, heat of the battery cells 101 is transferred to the housing 102 through the rubber sheet 106, and effectively removed by water cooling.